[Ischemic cortical neuronal damage and cognitive impairments in atherosclerotic occlusive disease of the major cerebral artery: a PET study].

In atherosclerotic internal carotid artery (ICA) or middle cerebral artery (MCA) disease, selective neuronal damage can be detected as a decrease in central benzodiazepine receptors (BZRs) in an apparently normal cerebral cortex. To investigate the association between cortical BZRs decreases and executive dysfunctions, we measured BZRs using positron emission tomography (PET) and (11)C-flumazenil in 60 non-disabled patients with unilateral atherosclerotic ICA or MCA disease and no cortical infarction. Using 3-dimensional stereotactic surface projections, we calculated the BZR index, a measure of abnormally decreased BZRs in the cerebral cortex within the anterior cerebral artery (ACA) or MCA territory, and found that it to be correlated with the patient's score on the Wisconsin Card Sorting Test (WCST). Based on the WCST results, 39 patients were considered abnormal (low categories achieved) for their age. The BZR index of the ACA territory in the hemisphere affected by arterial disease was significantly higher in abnormal patients than in normal patients. The BZR index of the MCA territory differed significantly between the 2 groups when patients with left arterial disease (n = 28) were analyzed separately. The BZR indices of the anterior cingulate gyrus and the middle frontal gyrus carrelated significantly and positively with the total number of WCST errors. In atherosclerotic ICA or MCA disease, selective neuronal damage that is manifested as a decrease in BZRs in the non-infarcted cerebral cortex is associated with executive dysfunction. PET imaging of BZRs is useful as an objective measure of cognitive impairments in atherosclerotic occlusive disease of the major cerebral artery.